Sporulation-inducing factor in slime mould Physarum polycephalum

Abstract

THE highly synchronous sporulation of Physarum polycephalum is an attractive model of cell differentiation. Virtually all of the nuclei in a starved plasmodium proceed in step through the sporulation process in response to a well defined stimulus, light^1–4. The regulatory mechanisms of this differentiation are unknown but several studies have been presented on the conditions necessary for sporulation. These have been reviewed by Sauer⁵, who concludes that two elements are necessary for sporulation, substrate and light. These must be applied sequentially. The substrate requirement is for starvation in the dark for at least 4 d in the presence of niacin and niacinamide⁴. The light requirement is for at least 4 h illumination by a 40 W fluorescent light. Sauer also cites unpublished results which suggest that the effect of illumination is a local one which cannot be transferred to an unilluminated, starved plasmodium or even from the illuminated half to the unilluminated half of the same plasmodium.